In cryptography, the Boneh–Lynn–Shacham signature scheme allows a user to verify that a signer is authentic. The scheme uses a bilinear pairing for verification and signatures are group elements in some elliptic curve. Working in an elliptic curve provides defense against index calculus attacks against allowing shorter signatures than FDH signatures. Signatures are often referred to as short signatures, BLS short signatures, or simply BLS signatures. The signature scheme is provably secure assuming both the existence of random oracles and the intractability of the computational Diffie–Hellman problem.